Respiratory device



March 3, 1953 B. B. HOLMES 2,630,129

RESPIRATORY DEVICE Filed Jan. 22, 1947 2 SHEETSS HEET 1 49 .I V I H 9 III 55 67 747050 6372 7879 30 INVENTOR BHHDFUHU HUL ME 5 ORNEY March 3, 1953 B. B. HOLMES RESPIRATORY DEVICE 2 SHEETSSHEET 2 Filed Jan. 22, 1947 INVENTOR BHHDFUHD HULMES RNEY Patented Mar. 3, 1953 RE SPIRATORY DEVICE,

BradfordzBS Holmes, New York, N. Y., assignor to Bendix Aviation :Gorporation; Teterboro; N: J acorporation .otDelaware- ApplicationJa'nuary 22, 1947, Serial No; 723331 ZILGlaims.

V This-- invention" relates to respiratory" devices and more particularlyto-anautomatic control for the' demand valve: of a dilutcr demand oxygen regulator;

Ill demand oxygen regulators used in flights over 10,060 feet 'to' supplement ithe' oxygen supply in these rarefied reg-ions, respiratory responsive members are employed to control the quantity of oxygen delivered to *the'mask: f Thesactuation of 1 the responsive members will .open and close 7 a demand valve which will permit the oxygen to flow into the maskfrom: a: reducing" chamber within =the-regulators In d-iluter demand: regn.- lators, theoxygen is mixed 6 with amquantityof air so that 1 an air 'oxygen mixture is delivered 'ItO them'asle;

Whom higher altitudes 1 are reached, the aire oxygen mixture'must be enriched; and the oxygen,

in; cases-= of extreme high altitudes, I delivered to the maskunder pressure to maintain alveolar which will tvary/ the operation of i the" regulator to deliver .tlie'oxygen toitheflmaslt at increasing pressuresws atmosplieric:pressure decreases;

A further object of my invention is to provi'de a pressure" responsive H controlfor" the" demand valveP-of a iegulatonwhioh sliall exert a positive' pressure on a the: respiratory; responsivei member controlling: the; demandivalve :for: increasing: the pressure of the oxygen delivered to thermaskrby thezregulator:

, Another obj ect of this invention lisetorprovide' a pressure responsive. control of; thetcharacteriindicated whichalight, positivelpressure isapplied to the. respiratory responsive member. control- 7 ling-the demandvalvetto provide oxv cnundera safety pressure offabout 25inch lofwateri'toprevent air intake due t'o a" mask leak :atiliigh, altitllds of 2 (1000120 33,000 T6817.

Still a further object ofthis inventioniis to i provide a pressure responsive control 'oftliechar actor"indicatedbvwliich' a positivepressure is."

2 applied to the respiratory responsive member controlling the demand valve to provide oxygen undr-pressureof from .25 to 12 inches of water to the maskat altitudes'from 33,000170 50;000 feet.

Stillanother object of this invention is to provide a pressure responsive control of the character indicated by' which a-large positive dome is applied to the-respiratory responsive: member controlling the demand valve toprovide super pressure oxygen at the" mask'at increasing pressures from 121to:56"inches, and'more, of "water; to permit'fi'i'ghts overthe-SGgOOO feet-level.

Yet another object of my invention -is--toprovide in a pressure responsive control of the character indicated with means wherebythe effective area of the respiratory responsive member controlling the demand valve ofa regulator upon which the positivepressure of'the control acts, is gradually reduced at" altitudes overapredeterrnined'higli altitude, to deliver oxygen at increasing super pressures to the mask.

Yet a -further object of this'inventionisto provide a highly improved and Irugged pressure: re-

sponsive control 1 for the demand" valve of an oxygen demand regulatorswhichshallibe' automatic and positive in its actions ,1 relativelyrinexpensive to manufacture; which shall have, a large variety of applications; and yet berpracticaland efficient to a high degree in use.

Other objects of the invention; will in: part be obvious, and in;part:hereinafter pointed out.

The invention accordingly consists :in the features of construction, combinations of elements, and arrangement of parts :whicha will lee-exemplified inthe construction hereinafter; described and" of. whichthe scope" of application 'wi11; be indicated in the: appended claims,

In the accompanying: drawings: forming: a part of this specification. in which one or the-various possible, illustrativeembodiments:of this invention .is shown, andwherein similar reference? characters: designate corresponding parts throughoutithe severalviews;

Figure, 1 is a vertical section of a pressurere- ,sponsive controlfora demandvalve embodying my invention,

Figure .2 is a view similar to Figure, 1 showing the action of. the control at an altitude, over 50,000 feet, while Figure. 3 is a schematicof a diluter, demand oxygen regulatorshowing the action of f my pressure responsive, control on the respiratory responsive diaphragmat'an altitude of .from 20;000 to 32;;000 feet.

Referring now" in detail to' the schematic" of valve seat 23.

body H.

with a diluter assembly 35 (Figure 3). diluter assembly comprises a'threaded cup memrying a plate valve 4!.

3 Figure 3, l6 designates a demand oxygen regulator housed in a cylindrical body ll having affixed thereto in a suitable manner the novel demand valve control l2.

The regu ator body II is provided with an oxygen inlet port [3 to which oxygen storage cylinders (not shown) may be afiixed and an outlet port it to which the hose line connecting the mask (not shown) may be attached. A pressure reducing valve i5 is provided in the inlet line l6 connected to the port l3 to reduce the pressure of the oxygen as delivered from the storage tanks. The valve I 5 is adapted to be actuated by a pressure responsive capsule it placed within a reducing chamber I9 located within the body of the regulator Ill. Expansion and contraction of capsule l8 due to the changes in the pressure within the chamber 9 will seat and unseat the valve on a valve seat formed in the inlet to the chamber !9. A line 2! connects the reducing chamber IS with a demand chamber 22.

The outlet of chamber 22 is provided with a Cooperating with said valve seat is a demand valve 24 fixed to a valve stem 25. A

coil spring 26 placed about the valve stem normally urges the valve against the seat 23. Pivoted to the upper end of the valve stem is a lever 23 which is pivoted as at 29 within the regulator The link 28 is adapted to be oscillated about the pivot 29 by a respiratory responsive diaphragm 3i) fixed across the open end of the cylindrical body ll forming a chamber 3| within the body.

The respiration of the mask wearer will cause the diphragm 3t to rise and fall to pivot the lever 25. Inspiration will reduce the pressure within the chamber 3| causing the diaphragm to fall. The lever 28 is thus pivoted in a counterclockwise direction to lift the demand valve 24 from the seat 23. The oxygen will then flow from the demand chamber 22 past the demand valve and into a line 32 as indicated by the arrows of Figure 3. Expiration will cause the diaphragm 30 to lift,

permitting the demand valve 24 to be seated shutting off the oxygen supply.

The oxygen line 32 leading from the demand valve terminates in a jet nozzle 33. The oxygen Lfrom the nozzle 33 is directed into the mouth of a venturi 3d.

Means is provided to mix the oxygen delivered by the nozzle 33 with a quantity of air.

To this end, the regulator body II is provided The ber 36 having a handle 3'! adapted to be rotated to close the plurality of air inlet ports 38 provided in the assembly; A chamber 39 within the assembly is provided with aneroid capsule 40 car- The plate valve 4| is adapted to be seated and unseated on a seat 42 formed in the outlet of the chamber 39. The capsule ll) will expand and contract with changes in barometric pressure. As the altitude increases the capsule will expand to reduce, and finally shut off the supply of air passing through the valve il, 62. The capsule as will seat the plate valve -13! at approximately 32,000 feet, the regulator it then delivering 100 percent oxygen at higher levels. The air leaving chamber 39 will flow into the venturi 34 through a line 43, a check valvei i l in said line prevents leakage from the regulator ill.

air-oxygen mixture flowing from theventuri en- 4 ters the outlet M of the regulator and thence out into the mask.

An emergency Valve 45 is placed in the oxygen inlet line l6. Opening of the valve 45 by the knob 46 will permit the oxygen to flow into and through the regulator body to the outlet port l4, bypassing the valve mechanisms hereinbefore described. j Y

For a further and more detailed description of the oxygen demand regulator and its operation, reference may be made to my copending application therefor, bearing Serial No. 482,016 filed on April 6, 1943.

Means is now provided for applying a positive pressure on the diaphragm 3% to decrease the suction required of the mask wearer in opening the demand valve 2 3, and to gradually increase the positive pressure applied as the atmospheric pressure decreases with increasing altitude for increasing the pressure of the oxygen delivered to the mask fixed to the-regulator outlet M.

'To this end, the pressure responsive control .member I2 is fixed over the diaphragm 39 of the regulator (Figures 1 and 2). The control member I2 is enclosed in a shell 4'! which is threaded to an upstanding threaded annulus 48 on the regulator body H. The lower portion of the annulus is provided with a series of ports it to permit ambient pressure to affect the control mechanism within the shell, as hereinafter described.

Fixed within the shell ll and to the top thereof, as by screws 50, is an abutment member 5 l. Held between said member and the top of shell 4! by the screws 50 is a circular plate 52 forming the top wall of an aneroid 53. The aneroid 53 is formed with corrugated side walls 54, an annular bottom wall 55 and an interior side wall 56. The interior wall 56 terminates at the top thereof in an annular member 51 which forms the top wall of a nested aneroid 58.

The aneroid 58 comprises a corrugated side wall 59, an annular bottom wall 69, and a cupformed interior wall Bl. Fixed dependently within the cup-formed wall 6! is a block 52, having fixed thereto as by screw 53, a U-shaped member 64 forming a spring guide member and abutment plate. 1

The response of the nested aneroids 53.and .58 to atmospheric pressure within the shell 41 due to the ports 49 is such, that aneroid 58will expand upon a decrease in pressure. before the aneroid 53 expands, as will hereinafter be de scribed. Both of the aneroids 53 and 53 are provided with internal calibrated springs 65 and 66, respectively, for aiding in applying a positive force to the diaphragm 30 as hereinafter described. r

The bottom wall 55 of the aneroid 53 has affixed thereto an annular ring plate 67. The plate 61 forms a stop for the aneroid 58, the wall thereof bottoming on plate 61 when said aneroid being clamped between them, as by post H and nuts 12; the plate 69 being of smaller diameter than that of plate 10. A large plate M is placed on the diaphragm plate 69 and .over the post and nuts 12. l

A light coil spring 15, hereinafter'referred toas the safety, pressure; spring, isrplaeed. about the U -shaped member 64, Lone:endfofithespringgbeing fixed to the iflaredi upon .endi-IB ofrsaid'imember;

while the lower end of. said 1 springisa welded to Sleeve 18 isathus; suspended:over-.the diaphragm surrounding the.- post- H and nuts-.12; the lower end oft the-.sleeve-rbeing spaced fromthe plate 74 asshown-inFiguraL A'second coil spring- 19; hereinafter. referred-toes the pressure} breathing: spring, is also disposed. Within? the cup-formed member 61 and iabouttther u shot-pod member 64 andsafetywpressurespring?15v. The:

upper end of-this spring is ifixedrto the flaredend 16',- whilethe lower. endiha'stwelded'theretqgor fixed in any suitable manner, {as ring 80,-,said.

18 when the tWoaneroids-BS and 58.are-scollapsed' With the aneroid- 5B bottomed fin aneroidr53= ring 80- is just. above: the. larger plate: llot.- the diaphragm .30, as indicated. in. the schematics?! Figure 3.

The regulator ID as herein.desoribedwill.

operate. to. deliver. an. air-oxygen mixture sea level to an altitudeof approximately 18,000 feet, the mixturetdelivered.maintaininggtliefoxygen. pressure in the. lungstof'tha-user. equivalent to that available from sealevel to the-2,500 foot level. The. suction required of the mask wearer is approximately .25. inch water. pressure for operating. the demand. valve; as. described. The

mixture ratio of. air: and oxygen wilLbevaxied as changes in altitude/takeuplace due. twthe' diluter assembly the plate valveifll duelto the expansiom-ot'the aneroid. 40' gradually reducing and completely shuttingaoffitherair; supply at approximately the-32g00olfoot level.

At approximately 18,000 feet, the aneroidit' tion of the. diaphragm. This positive pressure is reached. atapproximatelythe. 20g000-footlevel and is maintainediup to an altitude-otapproximately 32,000 feet. The aneroidii'fll will: bebfully expanded at about-22,000 feet; the=plate thereof bottoming on the ring B'l-of the aneroid;53. The ring fixed to the pressurebreathingvspring19' will. be lowered upon expansion: of the aneroid' 58, the ring however. fallinglshmteof abutting the. plate 'M-(FigureB) With thel ositive pressure built-111p in tthea'egsu lator, expiration of; the: user will? closer-the? ilemand valve 2 to shut off' the-voxygen supply momentarily. No suction isrequired:- to open the demand valve. There is'rthus -xprovided a positive pressuretwithinethemasketo compensate for mask leakage.

water within the regulator. is maintained a's the altitude increases. from' 22,000 feettotabout 32,000 to 33,000 feet.

affixed to the pressure breathing spring will en age the plate T4 to exert a. positive: force thereon; It will be remembered. that at this;-level,- the diluter assembly cuts off'the air supplyysoethat At' this. higher. level. the lar er aneroid 53-b'egins.t0 expand; The ring 80.

a :65 The small positive DIBSSUIE'Off .25. inches-pf 1.00 perceuta oxygezrismowtbeing; delivered ztosthe maskr.

The? force'rexentedi the: pressure breathing spring will gradually; inoreasethe pressure within theiiregulator until attan altitude of about 50,000 feet -the oxygen pressure delivered: by the. reg-v ulator ia about 12 inches 1 of. water. The oxygen delivered to the :masle atthese altitude levels is thus; at. a pressure:- suflioient to maintain the oxygen tension .in" the-Ylugsto prevent anoxaemia.

.Above .-the=altitude:of approximately 50,000 feet, thevserewtl in .the. abutment block 62. will abut the post 'll on thediaphragm 30 (Eigure 2). The continued expansion of. the aneroid 53 with increasing;altitude-will build. up a pressure. greater thantthathexertedby the spring-.liand 1.9 The pressurexwithi-n the regulator. will thus be built up.-.due.;to-the opera demand valve,;causing the edges.- of thediaphragmto-bulge. See Figure;2'. Thistwillalift the. plate 14 off the plate .691 against theebia-s'a'of. the'spri-ngs 15'. and: 19, t theedges of plate. "Arising against the: stops 82. provided intthe annulusxdll.

The pressure exerted by the aneroid 53- is balanced .tbythe regulator pressure multiplied by the. area o-Jthe pla=te 60 and the adjoining. area ofithe diaphragm -30. The area provided byplate 694s, smaller than-thatiprov-ided by plate. 14 when the. latter was effective. in applying the aneroid pressureseto theediaphragmt A greater pressure mayv thus be builtzupiinlthe regulator. Any desired range of "pressures may be attained by. making the plate 1590f -.suitable diameter;

A5 .0 the. altitude continues .to increase over the 50,0-00afootelevel,. no. expansion of. the aneroid will take place due to theeabutment of bottemwall 55..on-.the stops 82.= Howevengthe continue'd increaseiin altitude will affect-the aneroid .58 since the wall a 60 thereof: has separated. from plate 6! during the expansion. of aneroid 53 so that. an ever:inoreasingiforceisapplied to the post H, the pressurejbeingbalanced .-by the regulator pressure. Thepressure-in thexregulator will rise to about 56; inches; of water-at an. altitude of r 50,000 feet, andztotabout' 72. inches; at. an altitude of 100,000 feet permitting. sa-fe flights: at' these: extreme upper; levels It: wills thu .be' seen. that there isaprovided an oxy en: demand. regulator control in; which the several objects of this invention are achieved, and

whiehis welladapted to: meet the: conditions of practical use-a As. various: embodiments may, be made in" the above inventionand as. various changes mayrbe made in: the embodiment'above set' forth; it" is; to berunderstoodtthat allimatteriab'ove'set forth, or ShOWlIJ i11l the accompanying: drawings; is: to be interpreted:. as: illustrative and not :in a limiting sense:

HavingxthumdiescribedJmy invention; I claim as new randadesire :to secure by Letters Patent:

11 In awdemand regulator having a demand valvetcontrolled-bye respiratory responsive diaphragm; awe-combination of nested 1 pressure responsive members adapted to sequentially and them'coneurrently expand upon decrease in ambient pressure, means connecting said members toisaidmespiratory responsive diaphragm whereby the? e-iqtiansion of"said* membersapplies an increasing'positive: force to the respiratory responsire diaphragm as the .ambientzpressure decreases to openither demand .va lve controlled thereby.

Zt-Ini a: demand regulator having a demand valvetcontrol-led'; by a respiratory responsive? diaphra gm; .theecombination of; nested. pressurearee sponsive members adapted to sequentially and then concurrently expand upon decrease in ambient pressure, resilient means between said members and said respiratory responsive diaphragm for applying an increasing positive force to the respiratory responsive diaphragm as said nested members expand sequentially and then concurrently with decreasing ambient pressure to open the demand valve controlled thereby;-

3. In a demand regulator having a demand valve controlled by a respiratory responsive diaphragm, the combination of two nested pressure responsive members adapted to sequentially and then concurrently expand upon predetermined decreases in ambient pressure, resilientmeans for connecting one of said members to said respiratory responsive diaphragm, and means connecting the other of said members to said one mernber upon a predetermined 'decrease in ambient pressure, whereby an increasing positive force is applied to the respiratory responsive diaphragm as said nested members expand with decreasing ambient pressure to open the demand valve controlled thereby.

4. In a demand regulator having a demand valve controlled by a respiratory responsive diaphragm, the combination of a plurality of resilient members adapted to coact with the respiratory responsive diaphragm, and a plurality of interconnected pressure responsive means adapted to expand sequentially and then concurrently upon decrease in ambient pressure for biasing said resilient members to apply an increasing positive pressure on said respiratory responsive diaphragm to affect the control thereby of the demand valve.

5. In a demand regulator having a demand valve controlled by a respiratory responsive diaphragm, the combination of a plurality of resilient members adapted tocoact with the respiratory responsive diaphragm, and a plurality of interconnected pressure responsive means adapted to expand sequentially and then concurrently with decreasing ambient pressure for moving said members into sequential engagement with the respiratory responsive diaphragm and for biasing the same to apply an increasing positive force thereon to affect the control of the demand valve thereby with the continual decrease in ambient pressure.

6. In a demand regulator having a demand valve controlled by a respiratory responsive diaphragm, the combination of pressure responsive means adapted to expand with decreasing ambient pressure, a pair of resilient members carried by said pressure responsive means, and means carried by said members whereby saidumembers move into sequential and then concurrent engagement with the respiratory responsive diaphragm to bias the same to apply an increasing positive force thereon to afiect the control of the demand valve thereby upon expansion ofsaid pressure responsive means in response to a continual decrease in ambient pressure the force of each of said resilient members being applied between diilerent predetermined ambient pressure limits. Y

'7. In a demand regulator having a demand valve controlled by a respiratory responsive diaphragm, the combination of pressure responsive means adapted to expand with'decreasing am-' bient pressure, a pair of resilient members carried by said pressure responsive means, and means carried by said members whereby said members move into sequential and then concurrent en- 8 gage'nient with the respiratory responsive diaphragm to bias the same to apply a pressure thereon to affect the control of the demand valve thereby upon-expansion of said pressure responsive means in response to a continual decrease in ambient pressure, one of said resilient members applying an increasing pressure to said respiratory responsive diaphragm between predetermined ambient pressure limits, the other resilient member 'in conjunction with the first member applying a greater increasing pressure between lower predetermined ambient pressure limits than the first limits as the ambient pressure decreases.

8. In a demand regulator having a demand valve controlled by a respiratory responsive diaphragm, the combination of pressure responsive means adapted to expand with decreasing ambient pressure, a pair of resilient members carried by said pressure responsive means, and means carried by said members for moving said members into sequential and then concurrent engagement with the respiratory responsive diaphragm to bias the same to apply a pressure thereon to afiect the control of the demand valve thereby upon expansion of said pressure responsive means in response to a continual decrease in ambient pressure, one of said resilient members applying an increasing pressure to said respiratory responsive diaphragm between predetermined ambient pressure limits, the other resilient member in conjunction with the first member applying a greater increasing pressure between lower predetermined ambient pressure limits than the first limits as theambient pressure decreases, and abutment means on said pressure responsive member for applyinga still greater increasing pressure directly to the respiratory responsive diaphragm between still lower predetermined ambient pressurelimits as the ambient pressure continue to decrease.

9. In an oxygen demand regulator, the combination comprising, a respiratory responsive dia- "phra'gm, a demand valve operated thereby for controlling the oxygen supplied by the regulator, abutment plates for said diaphragm, resilient means adapted to coact with said diaphragm plates, pressure responsive means adapted to expand with decreasing ambient pressure for biasing said resilient means to apply a positive pressure to said diaphragm through said plates, and means on said pressure responsive means for reducing the effective area of said plates to increase the oxygen pressure in said regulator to balance the pressure on said diaphragm between predetermined limits of ambient pressure.

10. In an oxygen demand regulator, the combination comprising a respiratory responsive diaphragm, a demand valve operated thereby controlling the oxygen supplied by the regulator, abutment plates for said diaphragm, a plurality of resilient means adapted to apply positive pressures on said diaphragm through said plates pressureresponsive means adapted to expand with decreasing ambient pressure for biasing said resilient means against said plates, the pressure by said resilient means being sequentially and then concurrently applied between predetermined ambient pressure limits, and abutment means on said pressure responsive means to engagev said diaphragm plates between predetermined lower ambient pressure limits reducing sive means. I

, 1 l. mas -oxygen deniaIi'd re'giiIator inseam;- binaticn-comprising a respiratory respon d a"' phragm, a dem'a nd valveoperated thereb'y' c'on trolling the oxygen supplied by the regulator, an abutment plate =io'r said-diaphragm, two nested aner'oids in juxtaposition with 1 said diaphragm said aneroids being a dapted to expand sed'en many with" decreasing atmospheric-menu of said aneroids 'expandingand ottor'nin w hi i theother before the-second aneioid bgi expand, a pair-pfsprings carried by the inner aneroid, andmeans carriedby's d engageable with said -diaph'ragin i p pansion of said aneroids'whereby saidsprmgs and' aneroids apply sequentially and" their concur rently increasing positive-press phragm plate-toafiectthe con j valvebysaid diaphragm as-atme'spheric pressure decreases between predetermined *lim i 1 12; In an oxygen demand-regulatore com bination comprising arespiratory' responsiire dia phragm, ademand valve operatedther trolling the oxygen supplied bytheregul to abutment plate-for said-d iapluragrrr', a' post v fixing said plate to said diaphragm, affi second abutment plate of -larger area-than saidfirst plate on said first plate and movable with respect thereto and said post; elf-pressure responsive member in juxtaposition with said diaphragm adapted 'to expandwith decreasing atmospheric pressure, and. a member movable with said pressure responsive,mernberiadaptedto abut the post on-said diaphragm betweenspredetermined limits of atmospheric pressure, the 1 positive; pressure exerted on said post and said firstplate by the expansion: of saidam'ember: causing; said diaphragm to lift said second plate to decrease the effective area of positive pressure applicationion s'aiddiaphragm; U l

I 13. In an oxygen demand regulator mesmerination comprisinga -respiratorp responsive diaphragm, a demand valve operated thereby con-,- trolling the oxygen supplied:; b y the regulator; gan abutment plate for said diaphragm, a post for fixing said plate to said diaphragm, a second abutment plate of larger area than said first plate on said first plate and movable with respect thereto and said post, two nested aneroids in juxtaposition with said diaphragm, said aneroids being adapted to expand sequentially with decreasing atmospheric pressure, one of said aneroids expanding and bottoming within the other before the second aneroid begins to expand; said aneroids being adapted to apply sequentially and then concurrently increasing positive pressures on said second diaphragm plate to affect the control of the demand valve by said diaphragm as atmospheric pressure decreases between predetermined limits; and a member movable with said aneroids adapted to abut the post on said diaphragm between lower predetermined limits of atmospheric pressure, the positive pressure exerted on said post and said first plate causing said diaphragm to lift said second plate decreasing the effective area of positive pressure application on said diaphragm to increase the oxygen pressure within the regulator by the open demand valve for balancing the positive pressure applied by the nested aneroids.

14. In an oxygen demand regulator the combination comprising a respiratory responsive diaphragm, a demand valve operated thereby controlling the oxygen supplied by the regulator, an abutment plate for said diaphragm, a post for fixing said plate to said diaphragm, a second abutplate- 0f largr aia than" said first plate on said first-plate and rn'o'vable with r'es'pect there to n d said post; we nested aneroids mania position witlr sa id diaphragm; said aneroids b in'g adapted toexpasdsuuenuauywith decrea's mg atmospheric pressure; oneof said-' ane'roids expanding and bottoming with-in tl'le other-before s-itive? te o a ressu e ea'rstdapifl'y' a; positiveipressure on said diaphragirrwithin predetermined limits; said} secondfplate"being adapted to be 'liftedby said diaphragm"frbm"said" firstzplate to decreasei the f eifectivmpressure "areiiion said diaphragm when" the positivdpressure"is above' said predetermined limit 01ffpreSsureJ l6} man oxy en' reg atbr ortueaemans type having-a "casing including outlet 'adaptedfor connection to a breathing mask, a respiratory responsive diaphragm and a demand valve operatively connected to said diap S d demand valve normally controlled by respiratory pressure on said diaphragm, a control mechanism for said demand valve comprising a first and second aneroid on one side of said diaphragm, means carried by said second aneroid and engageable with said diaphragm for biasing said diaphragm to operate at reduced respiratory pressures at predetermined ambient pressures, and means connecting said first aneroid to said second aneroid whereby said first aneroid cooperates with said second aneroid below said predetermined ambient pressures to bias said diaphragm to override the respiratory control and open said demand valve.

17. An oxygen demand regulator adapted for use with a breathing mask, comprising a casing, a pressure chamber in said casing having a respiratory controlled diaphragm defining one wall thereof, a demand valve operatively connected to said diaphragm permitting the flow of oxygen into said chamber, an outlet from said chamber adapted for connection to said mask and providing for the flow of oxygen to said mask, a pair of nested interconnected aneroids, said interconnected aneroids expanding sequentially and then concurrently in response to decreasing ambient pressure, and means connecting said aneroid to said diaphragm upon the sequential and then concurrent expansion of said aneroids, whereby one of said aneroids biases said diaphragm to decrease the respiratory pressure required to operate saiddemand valve at a predetermined ambient pressure, and both of said aneroids are operative below said predetermined ambient pressure to bias said diaphragm to retain said demand valve in open position.

18. In an oxygen demand regulator having a casing adapted for connection to a breathing mask, achamber within said casing having a respiratory responsive diaphragm defining a wall of said chamber, an outlet from said chamber adapted for connection to a breathing mask, and a demand valve controlling the flow of oxygen into said chamber, a control mechanism for said demand valve comprising a lever mechanism operatively connected to said demand valve and to said diaphragm to open and close said demand valve, a plurality of interconnected aneroids set to distend sequentially and then concurrently at predetermined ambient pressures, and means carried by one of said aneroids and engageable with said diaphragm whereby the sequential and the concurrent expansion of said aneroids actuates said lever mechanism and. thereby operates said valve to control the oxygen pressure in said chamber.

19. In an oxygen regulator of the demand type having a casing adapted for connection to a breathing mask, a chamber in said casing communicating with said mask and having a diaphragm defining one wall thereof, a demand valve permitting the flow of oxygen into said chamber, a control mechanism for said demand valve comprising lever mechanism connected to said demand valve and to said diaphragm and cooperating therewith to open and close said demand valve, a pair of interconnected aneroids responsive to ambient pressure, said aneroids set to distend sequentially and then concurrently at diiferent desired altitudes, and means carried by one of said aneroids and sequentially and p then concurrently engageable with said diaphragm upon the sequential and then concurrent sure applied to said chamber, in combination interconnected therewith, a pair of nested aneroids set to distend sequentially and then concurrently in response to increasing altitude,

resilient means carried by one of said aneroids and engageable with said diaphragm, one of said aneroids set to distend at predetermined altitudes to engage said resilient means to said diaphragm and operate the same to increase the pressure to a desired value in said chamber, the remaining aneroid set to begin distending at higher altitudes to act in concert with said first aneroid and resilient means to operate said diaphragm to further increase the pressure in said chamber.

BRADFORD B. HOLMES.

' REFERENCES CITED The following references are of record in the file of this patent:

V V UNITED STATES PATENTS- Number Name Date 744,297 Cook Nov. 1'7, 1903 2,406,888 Meidenbauer Sept. 3, 19 46 FOREIGN PATENTS Number Country Date 611,546 Great Britain Apr. 30, 1946 

